The generation of formate from CO₂ provides a method for sequestration of this greenhouse gas as well as the production of a valuable commodity chemical and stabilized form of hydrogen fuel. Formate dehydrogenases are enzymes with the potential to catalyze this reaction; however they generally favor the reverse process, i.e., formate oxidation. By contrast, the formate dehydrogenase of the acetogen Clostridium carboxidivorans has been found to preferentially catalyze the reduction of CO₂. This is in accord with its natural role to introduce CO₂ as a carbon source in the Wood-Ljungdahl pathway. The direction of catalysis derives from the enzyme's low affinity for formate. This enzyme is therefore an excellent candidate for biotechnological applications aimed at producing formic acid and derivative chemicals from CO₂.
Keywords: CO2 fixation; CO2 reduction; Clostridium carboxidivorans; acetogens; formate dehydrogenase; formic acid; hydrogen storage.